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<td class="header">&nbsp; Range Shift<br>
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<h3>Sentinel-1 Range Shift</h3>
<p class="MsoNormal"><span>This operator follows the Backgeocoding
operator in the TOPS InSAR processing chain. It first estimates a
constant range offset for the whole sub-swath of the split S-1 SLC
image using incoherent cross-correlation. The estimation is done for
each burst using a small block of data in the center of the burst. The
estimates from all bursts are then averaged to get the final constant
offset for the whole image.<br>
</span></p>
<p class="MsoNormal"><span>The operator then performs shift in range
direction for every burst using the offset computed above with a phase
ramp method in frequency domain</span>.<br>
<span style=""></span></p>
 
<h4>Input <br>
</h4>



<ul>
<li>The input to this operator is the resulting product from the
Backgeocoding operator. It is the co-registered reference and secondary images
for the same
sub-swath and same polarization (e.g. IW1 -
VV). <br>
  </li>
</ul>

<h4>Output <br>
</h4>




<ul>
<li>The output of the operator are the co-registered reference and secondary
bands in I/Q format with the secondary bands shifted by a small amount in
range direction. <br>

  </li>
</ul>


<h4>Parameters Used<br>
</h4>




<ul>
  <li>Registration Window Width: Width of the sub-set of image used
for cross-correlation. <br>
  </li>
  <li>Registration Window Height: Height of the sub-set of image used
for cross-correlation. Larger window generally implies accurate
estimation of the range shift and also means larger memory and longer
processing time.</li>
  <li>Search Window Accuracy in Azimuth Direction: The search accuracy
in azimuth direction for the maximum correlation. The search window
height is 2*Acc.</li>
  <li>Search
Window Accuracy in Range Direction: The search accuracy in range
direction for the maximum correlation. The search window width is
2*Acc. .</li>

  <li>Window Oversampling Factor: The oversampling factor for the
search window. The larger the factor, the better the achievable
accuracy, and the larger the computation cost.<br>
  </li>
  <li>Cross-Correlation Threshold: Threshold
for normalized cross-correlation value. If the cross-correlation value
is greater than the threshold, then the estimated range offset is
considered valid, otherwise invalid.<br>
  </li>
</ul>
<img style="width: 450px; height: 450px;" alt="" src="images/RangeShiftUI.jpg"><br>

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